WASHINGTON (AP) — Anchorage, Alaska, was warmer Tuesday than Jacksonville, Florida. And it snowed Wednesday in Tallahassee, Florida, for the first time in 28 years.

The weather in the U.S. is that upside down.

That’s because the Arctic’s deeply frigid weather escaped from the atmospheric jail that traps the worst cold. It then meandered south to the central and eastern United States.

And this has been happening more often in recent times, scientists say.

WHY IS IT SO COLD?

Super cold air is normally locked up in the Arctic in the polar vortex, which is a gigantic circular weather pattern around the North Pole. A strong polar vortex keeps that cold air hemmed in.

“Then when it weakens, it causes like a dam to burst,” and the cold air heads south, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial firm outside Boston.

“This is not record-breaking for Canada or Alaska or northern Siberia — it’s just misplaced,” said Cohen, who had forecast a colder than normal winter for much of the U.S.

IS THIS UNUSUAL?

Yes, but more for how long — about 10 days — the cold has lasted, than how cold it has been. More than 1,600 daily records for cold were tied or broken in the last week of December, according to the National Oceanic and Atmospheric Administration. Far fewer all-time records were set. In other words, the minus 20 degrees in Omaha on Jan. 1 was the coldest New Year’s Day since record-keeping began in 1871. But that didn’t come near Omaha’s all-time record low of minus 32, set Jan. 5, 1885, according to the National Weather Service.

For Greg Carbin of the weather service’s Weather Prediction Center, the most meaningful statistic is the average temperature during the cold streak. In Nebraska, for example, Hastings, Lincoln and Grand Island had their coldest final week of December since record-keeping began in the late 1800s. Omaha, with only one daily temperature record that week, still managed to notch its third-coldest final week of the year. And remember, Omaha’s records go back to 1871.

IS IT JUST THE U.S.?

Pretty much. While the continental United States has been in the deep freeze, the rest of the globe has been toastier than normal. The globe as a whole was 0.9 degrees warmer than normal Tuesday and the Arctic was more than 6 degrees warmer than normal, according to the University of Maine Climate Change Institute.

WHAT’S THE LATEST?

Tallahassee got its first measurable snow in nearly three decades on Wednesday. The snow brought a childlike joy and wonder and loud whoops from longtime residents who rarely see the white stuff.

Much of the Southeast’s Atlantic Coast got a wintry mix of snow and freezing rain as the storm headed north.

The number of deaths linked to the relentless cold across much of the United States has risen to 17. The latest were in Texas, Mississippi and Michigan.

WHAT'S NEXT?

The weather service says an intense storm embedded in the system is expected to intensify so rapidly that it will qualify as a “bomb cyclone.” That’s one where the pressure at the center of a storm drops very rapidly.

The storm should dump at least 8 inches of snow today on Boston — where some flights are already canceled — and at least six inches on New York City.

Still, meteorologists say most of the storm’s fierce hurricane-force winds should stay out to sea until it nears Canada. Meteorologists say that perhaps the worst effects could be bitter subzero cold on the East Coast.

“For the Northeast, this weekend might be the coldest of the coldest with the storm,” said Jason Furtado, a University of Oklahoma meteorology professor. “We could be ending (the cold snap) with a big hurrah.”

WHAT MAKES THE POLAR VORTEX MOVE?

This is an area of hot debate and research among scientists and probably is a mix of human-caused climate change and natural variability, Furtado said. Climate change hasn’t made the polar vortex more extreme, but research indicates that global warming is allowing arctic air to make more prolonged, deep dives into the U.S.

That vein of research also indicates a possible connection between stalled weather systems at other times of the year. Global warming could be responsible for “stuck” spring and summertime weather patterns in which flooding rains or searing drought takes hold.

HOW CAN IT BE SO COLD WITH GLOBAL WARMING?

Arctic air is still bitterly cold, so atmospheric changes that allow that air to drop south will continue to lead to such sharp temperature drops. And don’t confuse weather — which occurs over a few days or weeks at a regional level — with climate, which spans over years and defines the region’s habitability. Weather is like a person’s mood, which changes frequently, while climate is like someone’s personality, which is more long-term, Furtado said.

“A few cold days doesn’t disprove climate change. That’s just silly. Just like a couple of down days on the stock market doesn’t mean the economy is going into the trash.”

World-Herald staff writer Nancy Gaarder contributed to this report, which also includes material from the Washington Post.

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March 23, 1913: Omaha Easter tornado

An estimated 103 people were killed and 350 injured in the Omaha area when the tornado struck with no warning on a warm Easter Sunday. About 750 of Omaha’s more than 2,000 damaged houses were destroyed. The tornado — now categorized by the National Weather Service as an F4 storm with 166- to 200-mph winds — was part of the most catastrophic outbreak of tornadoes in eastern Nebraska and western Iowa history. More photos.

Nebraskans experienced the worst of the Dust Bowl in July 1936. The state experienced scorching heat, with Omaha hitting 114 degrees. The city recorded 35 days that year with temperatures of 100 degrees or higher. Air conditioning was not yet common and people slept outdoors to catch a breeze.

Here, a dust storm approaches Naponee, Nebraska, in 1935. The large building is the First Congregational Church.

One of the worst blizzards on record suffocated all but southeast Nebraska. The region’s economy teetered on the edge of collapse as ceaseless winds and fresh snow defied efforts to keep roads and rail lines clear. Livestock by the tens of thousands died of starvation and exposure. Whole towns rationed food, and some residents burned furniture for household fuel.

Here, Vincent McKeown stands beside his car in a 20-foot deep snow canyon made by plows on Highway 275 10 miles west of Norfolk, Nebraska.

The storm raged across eastern Nebraska and caused deaths in five states. Omaha had just an inch of snow on the ground at 6 a.m. Jan. 10, but by 9 a.m. the city had declared a snow emergency. At one point an estimated 10,000 vehicles were stuck, stalled or abandoned in Omaha. Winds reached 60 mph, creating drifts as high as 10 feet. More than a foot of snow fell. More photos.

An F4 tornado with winds of more than 200 mph tore through a nine-mile-long section of Omaha, killing three people and injuring more than 100. Early detection, aided by storm spotters, helped prevent greater loss of life. The National Oceanic and Atmospheric Administration in 2013 ranked the damage as the eighth worst tornado in U.S. history at an inflation-adjusted cost of more than $1 billion. Read more.

Heavy, wet snow fell on still-leafy trees across southeastern Nebraska, resulting in downed tees, limbs and power lines. Streets were blocked, and houses and cars were damaged. The storm killed an estimated 3 percent of the Omaha-area’s trees and damaged another 30 to 35 percent. More photos.

Seen here is a snow-covered street and crushed trees near Miller Park in Omaha on Oct. 26, 1997.

Aric Brophy, left, of Aurora, Nebraska, raced outdoors to retrieve a hailstone and impress his kids. He came back with the then-largest hailstone on record for the U.S.: 7 inches across and 18.75 inches around.

Heavy snowmelt and record spring rains in the upper part of the Missouri River watershed overwhelmed levees and imperiled the six massive dams that control the Missouri’s flow. Flooding lasted four months and caused billions of dollars in damage.

U.S. Highway 136 is seen here running east of Brownville, Nebraska, over the Missouri River channel and into flooded Missouri farmland on July 15, 2011.

A long and lanky waterspout formed over Lake Manawa about 5:30 p.m., mesmerizing the many people in the metro area who saw it. After waltzing on the lake for 10 minutes or so, it broke apart. A spectacular sight, the tornado was harmless, because it had anchored itself to the lake. Had it not occurred in a populated area, the waterspout’s existence would have gone unrecorded. That’s because it was a rare tornado that formed independent of a supercell thunderstorm. It was so weak and out of place that it didn’t show up on radar, nor did it leave a trail of damage. More photos.

10 unusual weather events in the Midlands through the years

Nebraska and Iowa have had their share of unusual or extreme weather over the decades. Here are some examples.

— Compiled by Michael O’Connor

Source: Nebraska Weather, an Omaha World-Herald book

1 of 10

March 23, 1913: Omaha Easter tornado

An estimated 103 people were killed and 350 injured in the Omaha area when the tornado struck with no warning on a warm Easter Sunday. About 750 of Omaha’s more than 2,000 damaged houses were destroyed. The tornado — now categorized by the National Weather Service as an F4 storm with 166- to 200-mph winds — was part of the most catastrophic outbreak of tornadoes in eastern Nebraska and western Iowa history. More photos.

Here, people stand at 2410 Lake St. after the tornado.

DOUGLAS COUNTY HISTORICAL SOCIETY

July 1936: Dust Bowl

Nebraskans experienced the worst of the Dust Bowl in July 1936. The state experienced scorching heat, with Omaha hitting 114 degrees. The city recorded 35 days that year with temperatures of 100 degrees or higher. Air conditioning was not yet common and people slept outdoors to catch a breeze.

Here, a dust storm approaches Naponee, Nebraska, in 1935. The large building is the First Congregational Church.

NEBRASKA HISTORICAL SOCIETY

Jan. 2-3, 1949: Blizzard

One of the worst blizzards on record suffocated all but southeast Nebraska. The region’s economy teetered on the edge of collapse as ceaseless winds and fresh snow defied efforts to keep roads and rail lines clear. Livestock by the tens of thousands died of starvation and exposure. Whole towns rationed food, and some residents burned furniture for household fuel.

Here, Vincent McKeown stands beside his car in a 20-foot deep snow canyon made by plows on Highway 275 10 miles west of Norfolk, Nebraska.

THE WORLD-HERALD

April 1960: Flooding

Melting from a heavy winter snowfall led to widespread flooding across eastern Nebraska. Rivers were already swollen when rain, followed by up to 9 inches of snow, swept the area April 1.

The storm raged across eastern Nebraska and caused deaths in five states. Omaha had just an inch of snow on the ground at 6 a.m. Jan. 10, but by 9 a.m. the city had declared a snow emergency. At one point an estimated 10,000 vehicles were stuck, stalled or abandoned in Omaha. Winds reached 60 mph, creating drifts as high as 10 feet. More than a foot of snow fell. More photos.

Seen here are vehicles stalled on 72nd Street south of Dodge.

THE WORLD-HERALD

May 6, 1975: Omaha tornado

An F4 tornado with winds of more than 200 mph tore through a nine-mile-long section of Omaha, killing three people and injuring more than 100. Early detection, aided by storm spotters, helped prevent greater loss of life. The National Oceanic and Atmospheric Administration in 2013 ranked the damage as the eighth worst tornado in U.S. history at an inflation-adjusted cost of more than $1 billion. Read more.

Here, an aerial view of the Westgate area is seen on May 7, 1975.

ROBERT PASKACH/THE WORLD-HERALD

Oct. 26, 1997: Early snowstorm

Heavy, wet snow fell on still-leafy trees across southeastern Nebraska, resulting in downed tees, limbs and power lines. Streets were blocked, and houses and cars were damaged. The storm killed an estimated 3 percent of the Omaha-area’s trees and damaged another 30 to 35 percent. More photos.

Seen here is a snow-covered street and crushed trees near Miller Park in Omaha on Oct. 26, 1997.

RUDY SMITH/THE WORLD-HERALD

June 22, 2003: Super-sized hailstone

Aric Brophy, left, of Aurora, Nebraska, raced outdoors to retrieve a hailstone and impress his kids. He came back with the then-largest hailstone on record for the U.S.: 7 inches across and 18.75 inches around.

JAMES R. BURNETT/THE WORLD-HERALD

Summer 2011: Missouri River flooding

Heavy snowmelt and record spring rains in the upper part of the Missouri River watershed overwhelmed levees and imperiled the six massive dams that control the Missouri’s flow. Flooding lasted four months and caused billions of dollars in damage.

U.S. Highway 136 is seen here running east of Brownville, Nebraska, over the Missouri River channel and into flooded Missouri farmland on July 15, 2011.

MATT MILLER/THE WORLD-HERALD

Aug. 4, 2016: Lake Manawa waterspout

A long and lanky waterspout formed over Lake Manawa about 5:30 p.m., mesmerizing the many people in the metro area who saw it. After waltzing on the lake for 10 minutes or so, it broke apart. A spectacular sight, the tornado was harmless, because it had anchored itself to the lake. Had it not occurred in a populated area, the waterspout’s existence would have gone unrecorded. That’s because it was a rare tornado that formed independent of a supercell thunderstorm. It was so weak and out of place that it didn’t show up on radar, nor did it leave a trail of damage. More photos.